Peripheral Nervous Tissue - SD

Question 1

What is the name of motoneurons located in the ventral horn? What is the name of motoneurons in the intermediate or lateral position?

Answer 1

Ventral horn = somatic motoneurons

Intermediate and lateral position = visceral or autonomic motoneurons

Question 2

What is Nissl substance?

Answer 2

stacks of rough endoplasmic reticulum that are clustered with ribosomes; due to high amount of protein synthesis

Question 3

Where do most axon potentials originate?

Answer 3

Axon initial segment

Question 4

Where does the axon originate?

Answer 4

Axon hillock

Question 5

What are the functions of microfilaments (actin filaments) in the PNS?

Answer 5

Function to aid in cell movement, axon sprouting, positioning of receptors and ion channels at specific sites

Question 6

What are the functions of intermediate filaments in the PNS?

Answer 6

Most stable, function to stabilize and maintain neuronal morphology

Question 7

What are the functions of microtubules?

Answer 7

Most transient and least stable of the 3 cytoskeletal elements; note that that + end of microtubules in axons is the distal end. Function in intracellular transport, maintaining the constant diameter and axon elongation

Question 8

What cytoskeletal elements serves as tracks for motors that drive the transport of materials in axons?

Answer 8

Microtubules (they are more stable in neurons due to expression of microtubule associated proteins)

Question 9

What proteins are the motors for movement of cargo away from the cell body? What proteins are the motors for moving cargo towards the cell body?

Answer 9

Kinesins are the motors for movement away from the cell body (towards the + end of the microtubule; anterograde)
Dynein-dynactin complexes are the motors for movement towards the cell body (toward the - end of microtubule; retrograde)

Question 10

What is delivered via fast anterograde transport?

Answer 10

Materials essential for membrane function and maintenance (e.g. synaptic vesicle precursors, dense core vesicles, neurotransmitters, membrane associated enzymes, channel proteins)

Question 11

What is delivered via fast retrograde transport?

Answer 11

Autophagosomes deliver materials for degradation by the cell via fast retrograde transport
Growth factors and trophic substances move via fast retrograde transport which are critical for neuronal survival

Question 12

What is delivered via slow anterograde transport?

Answer 12

Microtubules and neurofilaments move via slow transport, as well as actin, clathrin, glycolytic enzymes

Question 13

What are organelles that move bidirectionally?

Answer 13

Mitochondria, late endosomes, lysosomes, as well as mRNAs

Question 14

What are the 3 layers surrounding peripheral axons?

Answer 14

Epineurium
Perineurium
Endoneurium

Question 15

What types of collagen are associated with the epineurium? The endoneurium?

Answer 15

Type 1 collagen in epineurium

Type 3 collage in endoneurium

Question 16

Where are gap junctions concentrated in the myelinated axon?

Answer 16

Concentrated at the Schmidt-Lanterman cleft.

Question 17

Where does the long process of the pseudounipolar DRG neuron go? Where does the short process connect to?

Answer 17

Long process goes to the peripheral nerve endings, short process goes from DRG neuron to spinal cord via dorsal roots

Question 18

Histologically, which cell type has more satellite cells, DRG cells or autonomic cells?

Answer 18

DRG cells are completely surrounded by satellite cells

Autonomic cells have satellite cells but they are more sparse

Question 19

What is the name of enteric cells in the submucosa? What is the name of enteric cells in the space between circular and longitudinal muscle layers?

Answer 19

Submucosa = Meissner’s plexus

In between muscular layers = Auerbach’s plexus